At present, airlines need to be able to adapt the passenger cabin of a given aircraft as a function of occupancy rates in the various comfort and tariff classes.
Thus, between two consecutive flights, airlines frequently need to change tourist class seats for business class seats, for example, or vice versa. Various methods and devices are presently available for that purpose. The first method consists in removing the seats entirely and in replacing them with seats of a different size. Such changeovers take too long and cannot in general be performed by crew members. That type of changeover is generally performed by specialized personnel during overnight maintenance.
In order to improve productivity, airlines are now tending to reduce stopover times between two flights quite considerably, since the cost of an airplane on the ground severely degrades productivity.
U.S. Pat. No. 3, 893,729 relates to a structure comprising a plurality of adjacent seats that are convertible between different comfort class sizes. That structure includes a support underframe carrying a plurality of adjacent seats. Each seat is independent from the others. Changing over to a higher comfort class consists in removing certain seats from each row (e.g. two seats from a row of eight), causing all of the remaining seats to slide along the support underframe, and adding an additional element to each of them for the purpose of increasing their width. The seats that have been removed are stored in the airplane's cargo hold. Such devices make it possible to perform maintenance operations more quickly and may even be performed by crew members. There nevertheless remains the need to put the seats that have been removed into the cargo hold and to bring out the additional elements needed for widening the remaining seats.
In addition, that type of device is convertible only and does not allow for the general size of the structure to be reduced on changing from eight adjacent seats to six wider seats.
EP-A-0 322 930, EP-A-0 433 664, EP-A-0 530 923, and EP-A-0 530 920 relate to structures comprising a plurality of adjacent seats suitable for public passenger vehicles, and combining convertibility with size reduction.
Those structures comprise a fixed portion comprising at least two transverse underframes that are spaced apart, fixed to the floor of the cabin, and connected rigidly to one another by longitudinal underframe elements having a general axis parallel to a sliding axis. The structure includes a moving portion comprising at least one tube that is coaxial with the longitudinal elements, slidably engaged with the longitudinal elements of the underframe, and carrying a plurality of adjacent rigid seat frames. The structure also includes a locking and release mechanism placed at one end of the first seat frame. Operation is as follows: by acting on the locking and release mechanism, the tube or tubes is/are allowed to slide in the longitudinal underframe elements, thereby providing a structure of a size that can be varied by moving the adjacent seat frames towards one another or away from one another. The convertibility function is achieved by sacrificing a seat onto which two arm rests are brought so that the two seats immediately adjacent thereto gain extra width.
Such a structure relies on a sliding coupling with tube engagement. The drawback of tube engagement is that it is difficult to maintain, and in particular to clean. Accumulated dust can cause tube-on-tube sliding to jam.
Another drawback comes from the fact that sliding takes place over a substantial fraction of the tubes. Consequently, the slightest deformation of one or other of the tubes, particularly the long-term effect of the repeated application of the weight of various occupants of the seats, tends to make axial sliding difficult.